mptcp: attach subflow socket to parent cgroup (3764b0c5) · Commits · 戴 / test

It has been observed that the kernel sockets created for the subflows (except the first one) are not in the same cgroup as their parents. That's because the additional subflows are created by kernel workers. This is a problem with eBPF programs attached to the parent's cgroup won't be executed for the children. But also with any other features of CGroup linked to a sk. This patch fixes this behaviour. As the subflow sockets are created by the kernel, we can't use 'mem_cgroup_sk_alloc' because of the current context being the one of the kworker. This is why we have to do low level memcg manipulation, if required. Suggested-by:

Matthieu Baerts <matthieu.baerts@tessares.net> Suggested-by:

Paolo Abeni <pabeni@redhat.com> Acked-by:

Matthieu Baerts <matthieu.baerts@tessares.net> Signed-off-by:

Nicolas Rybowski <nicolas.rybowski@tessares.net> Signed-off-by:

Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by:

Jakub Kicinski <kuba@kernel.org>

net/mptcp/subflow.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -1167,6 +1167,30 @@ failed:
		return err;
		}

		static void mptcp_attach_cgroup(struct sock parent, struct sock child)
		{
		#ifdef CONFIG_SOCK_CGROUP_DATA
		struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
		*child_skcd = &child->sk_cgrp_data;

		/* only the additional subflows created by kworkers have to be modified */
		if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
		cgroup_id(sock_cgroup_ptr(child_skcd))) {
		#ifdef CONFIG_MEMCG
		struct mem_cgroup *memcg = parent->sk_memcg;

		mem_cgroup_sk_free(child);
		if (memcg && css_tryget(&memcg->css))
		child->sk_memcg = memcg;
		#endif /* CONFIG_MEMCG */

		cgroup_sk_free(child_skcd);
		child_skcd = parent_skcd;
		cgroup_sk_clone(child_skcd);
		}
		#endif /* CONFIG_SOCK_CGROUP_DATA */
		}

		int mptcp_subflow_create_socket(struct sock sk, struct socket *new_sock)
		{
		struct mptcp_subflow_context *subflow;
		@@ -1187,6 +1211,9 @@ int mptcp_subflow_create_socket(struct sock sk, struct socket *new_sock)

		lock_sock(sf->sk);

		/* the newly created socket has to be in the same cgroup as its parent */
		mptcp_attach_cgroup(sk, sf->sk);

		/* kernel sockets do not by default acquire net ref, but TCP timer
		* needs it.
		*/

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